1. **Problem:** Compare the segments MR and RP in triangle MRP with angles 21° at R and 19° at P. 2. **Formula and rule:** In any triangle, the side opposite the larger angle is longer. 3. **Step:** Angle at R is 21°, angle at P is 19°. 4. **Step:** Since 21° > 19°, the side opposite angle R (which is segment MP) is longer than the side opposite angle P (which is segment MR). 5. **Step:** Segment MR is opposite angle P (19°), segment RP is opposite angle M (which is 180° - 21° - 19° = 140°). 6. **Step:** Angle M = 140° is largest, so side RP opposite angle M is longest. 7. **Conclusion:** RP > MR. Final answer: $\boxed{RP > MR}$